Optimization of PM2.5 Pollution Control in Residential Buildings Through Mechanical Ventilation Systems Under High Outdoor PM2.5 Levels in Chinese Cities

High outdoor PM2.5 levels in Chinese cities pose significant challenges to maintaining healthy indoor air quality in residential buildings, where mechanical ventilation systems are increasingly adopted for pollution control. In this paper, to control the indoor PM2.5 concentration, a mass balance equation for the non-uniform mixing model has been established to calculate the filter efficiency. This study aims to optimize PM2.5 pollution control in residential buildings through mechanical ventilation systems by evaluating the synergistic effects of filter efficiency and ventilation air flow rates under high outdoor PM2.5 conditions. Field measurements and numerical calculations were conducted to monitor indoor and outdoor PM2.5 concentrations. Results showed that, When outdoor PM2.5 concentrations remain below 100 μg/m3, an air exchange rate of 3 h−1 effectively maintains indoor PM2.5 levels below 35 μg/m3 for M6-F8 air filters. Experimental data demonstrate that when a fresh air system equipped with H10 filters operates at an outdoor PM2.5 concentration of 150 μg/m3, the corresponding optimal ventilation rate is 0.45 h−1. Increasing the mechanical ventilation rate to 1 h−1 enables the system to effectively handle higher outdoor concentrations up to 176 μg/m3. Under severe pollution scenarios with outdoor PM2.5 concentrations reaching 250 μg/m3, the air exchange rate should be further increased to 1.65 h−1 to maintain indoor PM2.5 concentrations within acceptable limits. This study provides practical insights for improving residential indoor air quality under high outdoor PM2.5 conditions in Chinese cities.